[Interrelations between monoamines and luliberin in the synaptosomes of the medio-basal hypothalamus and its separate structures]. / Vzaimosviaz' monoaminov i liuliberina v sinaptosomakh medial'no-bazal'nogo gipotalamusa i ego otdel'nykh strukturakh.

A study was made of the mechanism of interrelationship of neuromediators (biogenic amines) and LH-RH at the level of separate hypothalamic regions involved in the regulation of gonadotropic function of the hypophysis as well as at the synaptosomal level of the mediobasal hypothalamus (MBH). The steroid-dependent nature of LH-RH response in the investigated structures to monoamine administration has been shown. Noradrenaline and dopamine lowered the LH-RH level in intact animals in the area of arcuate nuclei and MBH synaptosomes, the LH level in the blood increased under the influence of noradrenaline only. Castration caused an increase in the LH-RH content in the arcuate area and its decrease in MBH synaptosomes; under such experimental conditions the LH level in the blood did not change. Serotonin in intact animals lowered the LH-RH level in the area of arcuate nuclei and MBH synaptosomes whereas in castrated animals the LH-RH level in the area of arcuate nuclei increased and decreased in synaptosomes.

[Luliberin of the synaptosomal fraction of the mediobasal hypothalamus in male rats and a change in its level as affected by monoamines]. / Liuliberin sinaptosomal'noi fraktsii mediobazal'nogo gipotalamusa krys-samtsov i izmenenie ego urovnia pod deistviem monoaminov.

Investigation of the effects of injecting monoamines (noradrenaline, dopamine and serotonin) into the third ventricle of the brain on the LH-RH content in the synaptosomal fraction of the mediobasal hypothalamus in intact and castrated male rats has demonstrated that all the three monoamines are involved in the regulation of synthesis and secretion of LH-RH and that their effects on LH-RH-producing neurons are steroid-dependent.

[Effect of monoamines on luliberin levels in various parts of the hypothalamus of the male rat]. / Vliianie monoaminov na soderzhanie liuliberina v razlichnykh otselakh gipotalamusa samtsov krys.

The effect of the monoamines--noradrenaline, dopamine and serotonin, injected into the third cerebral ventricle, on luliberin (LH-RH) content in the individual hypothalamic regions and the blood luteinizing hormone (LH) level, was studied in male rats. A reduced LH-RH level in the median eminence area and enhanced blood LH concentration were seen after noradrenaline injection. The number of cases where LH-RH level could be detectable in the blood, augmented following dopamine injection. The results obtained evidence that noradrenaline and dopamine participate in regulation of LH-RH synthesis and secretion and therefore in regulating the hypophyseal gonadotropic function.

[Role of sex hormones in realizing the monoamine effect on the luliberin content in the hypothalamus]. / Rol' polovykh gormonov v osushchestvlenii vliianiia monoaminov na soderzhanie liuliberina v gipotalamuse.

Drastic decrease in the level of sex hormone in the blood of castrated male rats lessened the content of LH-RH in the arcuate nuclei and median eminence of the hypothalamus. Obviously, this area is the place affected by androgens within the system of the negative feedback mechanism. Intraventricular noradrenaline had a stimulating effect on the synthesis and secretion of LH-RH in both intact and castrated animals. Meanwhile in the absence of sex steroids that action was less powerful. Dopamine stimulated the release of LH-RH from the terminals of the median eminence in all the groups of the animals. In intact animals, serotonin had no effect on the content of LH-RH, while in the castrated animals, it produced an inhibitory action on the synthesis and secretion of LH-RH. The results indicate that the intensity and the line of the effects of monoamines under study may depend to a certain extent on the animals endocrine status. The effects of monoamines on LH-RH neurones is steroid-dependent.